Robotic Arm Force Torque Sensing System (RAFTSS)

Motiv Space Systems (Motiv) proposes a novel, space-rated, load sensing system that will enable the next generation of space-borne robotic end effectors: The Robotic Arm Force Sensor Torque Sensing System (RAFTSS). Because the RAFTSS is designed with robotic, space-based applications as the primary application, it will advance the current state of the art in on-orbit servicing, assembly, and manufacturing. The novel solutions in the RAFTSS systemincludes: Wide-Range 6-Degree-of-Freedom (W6D) FTS. This sensor can be conceptually thought of as the wrist sensor. It can sense a broad range of imparted loads incurred during servicing and contact/capture operations (tens to hundreds of Newtons) with overload capabilities of 100 times the sensing range. Point of Application (POA) 3-DOF load sensors. These sensors can be thought of as the fingertip sensors of RAFTSS that are integrated directly into a tool or end effector gripper. Their load sensing ranges and axes can be tailor designed to directly measure minute loads imparted by delicate servicing operations or low mass payload acquisition operations (tens of Newtons). Co-located electronics that not only condition the RAFTSS signals, but also processes and resolves the loads into meaningful operational loads at the point of interest (i.e. at the end effector). This collaborative sensing approach addresses the primary challenges typically associated with force torque sensing systems. Morespecifically, designing systems capable ofachieving accuracies and sensitivities at levels sufficient to support mission objectives while being robust enough to handle overload conditions typically associated with launch environmmentsand large masses integrated at the distal end of robotics has been challenging. Existing space-borne robotic force and moment sensing systems face similar design and implementation challenges inherent in their application: They must be sensitive and accurate enough to support their mission objectives yet they must also support 1g testing/integration loads and survive the launch environment with typically large masses attached distal to their location, thus imparting very large dynamic loads during launch. The RAFTSS disentangles these competing challenges: The POA sensors are compact, multi-axis, load sensors that can be placed locally The W6D FTS can be thought of as a multi-rate flexure system This allows for a custom multi-range 6-DOF FTS CTE-matched foil strain gages are employed with standard aerospace metallic materials The RAFTSS co-locates its electronics at the sensor. Robotic mission designers no longer have to contend with the end effector mass driving the sensitivity of their system due to launch loads. The RAFTSS will be a game changer for space robotics system design. The primary technical objectives of this Phase 2 SBIR proposal are the following: From the results of the SBIR I efforts, evolve the W6D and POA sensors of the RAFTSS into a next generation path to flight set of hardware articles. Fabricate and assemble 2nd Generation load sensors (both W6D and POA) that incorporates the major sensing elements of the flight RAFTSS system. Demonstrate compatibility with a path to flight Force Toque Sensor Electronics package as a completely integrated solution. Work Plan: Design and Fabricate 2nd Generation of W6D and POA sensors evolving from Phase I results Leverage existing path-to-flight xLink Force Torque Sensor conversion electronics for RAFTSS Build an EDU platform that supports both POA and W6D sensors Perform integration and test activities between sense electronics and sensors (POA and W6D) Integrate upgraded EDU FTS electronics with 2nd Generation POA and W6D The prototypes and support equipment will have means of repeatably applying load conditions analogous to on-orbit use cases. Execute a test program to calibrate and characterize the load sensing capabilities of the RAFTSS prototypes Proposed Deliverables: Final Report Integrated RAFTSS System inclusive of (1) W6D, (1) POA, and (1) FTS Electronics Assembly
Benefits: Force torque sensors are critical components in autonomous, or semi-autonomous, robotic systems. As NASA pushes towards an increased use of autonomous robots in space, the RAFTSS will solve the pressing need for high sensitivity with high overload capability seen in almost every space robotics application. The NASA based market includes a broad swath of mission applications from on-orbit manipulation for servicing applications to sample capture needs for remote planetary sample and return missions. The non-NASA space market includes both private space companies and foreign space agencies. Private companies are increasingly taking roles in on-orbit assembly, debris removal, and satellite servicing tasks. These tasks require the use of advanced robotic systems which could benefit from the inclusion of the RAFTSS system.